A number of oxidizer salt-containing compositions, intended for use as blasting agents or explosives generally are known in the art. A number of patents which disclose representative ammonium nitrate-containing emulsions include U.S. Pat. No. 3,161,551, No. 3,447,978, No. 3,674,578, No. 3,715,247, No. 4,008,108, No. 4,104,092, No. 4,111,727, No. 4,218,272 and Canadian Pat. No. 804,541. Each of these patents discloses one or more variations on the general emulsion preparation of ammonium nitrate, water and a fuel oil, and these compositions are generally well known in the art.
A number of additional patents highlight the improved results which accompany the inclusion of a specific additive in the ammonium nitrate/water/oil emulsions discussed above. U.S. Pat. No. 4,110,134 to Wade includes waxes and closed cell void-containing material. U.S. Pat. No. 4,138,281 incorporates microbubbles in the ammonium nitrate-containing emulsion; Canadian Pat. No. 862,669 discloses the incorporation of hollow glass particles in the emulsified ammonium nitrate-containing compositions. U.S. Pat. No. 4,181,546 to Clay discloses the use of high shear to minimize emulsifier inclusion. Canadian Pat. No. 933,780 discloses a method for making blasting agents thixotropic. U.S. Pat. No. 4,149,917 to Wade discloses a water-in-oil explosive composition having no sensitizer other than occluded air. U.S. Pat. No. 3,765,964 to Wade discloses the use of strontium ion as a detonation catalyst. U.S. Pat. No. 3,770,522 discloses the use of a stearate salt emulsifier such as sodium stearate. U.S. Pat. No. 4,149,916 to Wade identifies inorganic perchlorate as an advantageous co-constituent with ammonium nitrate. U.S. Pat. No. 4,216,040 to Sudweeks et al. discloses the use of emulsifiers having unsaturated hydrocarbon chains therein, such as fatty acid amine or ammonium salts. U.S. Pat. No. 4,357,184 to Binet et al. discloses the use of an amphiphatic synthetic polymeric emulsifier. U.S. Pat. No. 4,404,050 to York et al. discloses the incorporation of unrefined or partly refined petroleum products, for example, slackwax, in emulsion explosives in addition to or in substitution for refined petroleum fuels. U.S. Pat. No. 4,420,349 to Bampfield discloses the use of a dimer acid glyceride emulsifier. U.S. Pat. No. 4,102,240 to Cook et al., entitled "Blasting Slurried Pump Truck," discloses a pump truck for handling aqueous slurry blasting agents which mixes and pumps the compositions into the on-site boreholes.
Three U.S. Patents disclose the use of various fatty acid salts as emulsifying agents in emulsion-type explosive compositions. These patents are U.S. Pat. No. 4,141,767 to Sudweeks et al., U.S. Pat. No. 4,287,010 to Owen, II, and U.S. Pat. No. 4,555,278 to Cescon et al. Sudweeks et al. disclose the use of a fatty acid amine or ammonium salt emulsifier having a chain length ranging from 14 to 22 carbon atoms. Owen, II discloses the in situ preparation of a fatty acid salt by the agitation of oil in the presence of a fatty acid and an ammonium or alkali metal hydroxide. Cescon et al. also disclose the in situ preparation of a fatty acid salt of an alkali metal, ammonium or alkylammonium compound. The fatty acid salt emulsifiers enhance uniformity and stability of the final emulsion and product.
Unfortunately, when ammonium nitrate and other oxidizer salts known in the art are emulsified with water, fuel oil, and emulsifier, emulsions generally tend to form with a wide distribution of particle sizes. These nonuniform emulsions demonstrate instability in that the ammonium nitrate or other oxidizer salt regularly appears as a solid precipitate out of the discontinuous phase, presumably as a direct or indirect result of the wide particle size distribution. The absence of uniform fine particles, moreover, thwarts optimum detonation. Lack of storage stability and optimal detonation capacity are, of course, serious commercial obstacles in the preparation and distribution of these explosives.
A need remains, therefore, for a method of producing an emulsion-type explosive composition, and for an emulsion-type explosive composition produced therewith, wherein the known and widely-used constituents of the emulsion-type explosive composition may be emulsified in such a way as to give uniform fine emulsions, improved storage stability, and maximized detonation capacity.